Power control for hybrid motorcycle

ABSTRACT

An automatic centrifugal clutch is interposed in a power transmission system between an engine and a driving wheel. A motor, which is capable of generating electricity, is supplied with electricity from a battery to generate auxiliary power. The motor is connected to a crankshaft of the engine. An acceleration data acquisition component acquires the accelerator operation amount and the accelerator operation speed. A rotational speed detection component detects the speed of the crankshaft. A rotational speed estimation component is adapted to estimate the engagement completion rotational speed, which is a rotational speed at which the automatic centrifugal clutch is completely engaged, based upon the acceleration data acquired by the acceleration data acquisition component. A motor controller supplies the motor 13 with a magnitude of electricity in accordance with the acceleration data when the rotational speed detected by the rotational speed detection means has reached the engagement completion rotational speed estimated by the rotational speed estimation component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 USC §119(a)-(d) from Japanese Patent Application No. 2006-217915, filed onAug. 10, 2006, which is hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to hybrid motorcycles featuringan engine and a motor. More particularly, the present invention relatesto such motorcycles in which the supply of auxiliary power from themotor is controlled to reduce the likelihood of automatic clutchslippage.

2. Description of the Related Art

A conventional hybrid vehicle run by power from an engine and auxiliarypower from a motor is disclosed in, for example, JP-A-2000-287306. Themotor of the vehicle disclosed in JP-A-2000-287306 is connected to acrankshaft of the engine and operation of the motor is controlled by acontrol device. Auxiliary power from the motor and power from the engineare combined at the crankshaft and the combination is transmitted to adriving wheel as a resultant force. A power transmission system betweenthe engine and the driving wheel includes a manually operable clutch.

The vehicle disclosed in JP-A-2000-287306 is run primarily by power fromthe engine, to which the power from the motor is added when the vehiclebegins moving in order to increase the driving force. The control deviceturns the motor to generate a predetermined torque when predeterminedstarting conditions are satisfied. One of the starting conditions forthis vehicle is that the manually operable clutch is engaged.

A clutch switch can be used to detect whether or not the clutch isengaged. In general, in vehicles such as automobiles, a clutch isdisengaged when the operator presses a clutch pedal, and the clutchswitch detects displacement of the clutch pedal or displacement of adetection element integrated with the clutch pedal.

SUMMARY OF THE INVENTION

The present inventors considered providing a scooter-type hybridmotorcycle utilizing the conventional technique for hybrid vehiclesdescribed above. The scooter-type motorcycle, however, is provided withan automatic centrifugal clutch, rather than a manually operable clutch.The automatic centrifugal clutch is positioned in the power transmissionsystem between the engine and the rear wheel. For at least this reason,as explained in more detail below, it has not been easy to realize ascooter-type hybrid motorcycle.

Different from the engine, the motor generates large torque atrelatively low speed. Thus, if the clutch is not completely engaged whenapplying auxiliary power from the motor when the motorcycle startsrunning, transmission of this large torque causes friction members inthe clutch to slip, which makes it difficult, if not impossible, for themotorcycle to start moving. That is, if it is not possible to accuratelydetect when the automatic centrifugal clutch is completely engaged, thatwould be a problem in realizing a scooter-type hybrid motorcycle.

The clutch switch used in JP-A-2000-287306 merely detects displacementof a manually operable member, and thus cannot detect when the automaticcentrifugal clutch is completely engaged. Even if the clutch switchcould detect the time when engagement is complete, providing such aclutch switch would increase the cost, and if the clutch switch failed,auxiliary power could not even be applied in the desired manner.

Therefore, one object of an embodiment of the present invention is toprovide a hybrid motorcycle with excellent start and accelerationperformance in spite of including an automatic centrifugal clutch.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of embodiments of thepresent invention will be described below with reference to the attacheddrawings. The drawings comprise the following figures.

FIG. 1 is a side view of a hybrid motorcycle that is arranged andconfigured in accordance with certain features, aspects and advantagesof the present invention.

FIG. 2 is a horizontal cross sectional view of a power unit used in thehybrid motorcycle of FIG. 1.

FIG. 3 is a block diagram showing a possible configuration of a controlsystem of the hybrid motorcycle of FIG. 1.

FIG. 4 is a block diagram showing a possible configuration of amotor/generator control section of the control system of FIG. 3.

FIGS. 5(A)-5(C) are graphs that explain how to estimate an engagementcompletion rotational speed in one configuration in which FIG. 5(A) is amap used to obtain a first rotational speed based on the APS angle, FIG.5(B) is a map used to obtain a second rotational speed based on the APSchange rate, and FIG. 5(C) is a graph showing changes in actualengagement completion rotational speed based on the first rotationalspeed and the second rotational speed.

FIG. 6 is a graph showing a relationship between APS angle and drivingcurrent for a motor.

FIG. 7 is a graph showing a relationship between a charge level of abattery and an electricity supply time to the motor.

FIG. 8 is a graph showing a map for obtaining the charge level of thebattery based on an open circuit voltage of the battery.

FIG. 9 is a graph showing a map for obtaining the charge level of thebattery based on a battery current and a battery voltage.

FIG. 10 is a graph showing a map for setting a charge current and adischarge current for a charge level of the battery.

FIG. 11 is a flowchart explaining the operation of the hybrid motorcycleof FIG. 1.

FIG. 12 is a flowchart explaining the operation of the control deviceafter engine start such that auxiliary power can be applied by operationof the motor.

FIG. 13 is a time chart explaining the operation of the hybridmotorcycle of FIG. 1 when the accelerator is operated such that theaccelerator operation amount increases generally in proportion to timefrom start to finish.

FIG. 14 is another time chart explaining the operation of the hybridmotorcycle of FIG. 1 when the accelerator is reversed slightly duringits movement from start to finish such that the accelerator does notsmoothly increase from start to finish.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference initially to FIG. 1, a hybrid motorcycle 1 comprises afront wheel 2 that is supported by a front fork 3. The front fork 3 isconnected to steering handlebars 4. The hybrid motorcycle 1 alsocomprises a rear wheel 5, which also may be referred to as the drivingwheel in the illustrated embodiment. A power unit 6 is supported by thehybrid motorcycle 1 and is connected by a driveline to the rear wheel 5in the illustrated configuration. The hybrid motorcycle 1 also comprisesa seat 7 and a body cover 8.

The front wheel 2 can be steered to the left and right by rotating thesteering handlebars 4. An accelerator grip 9, which can be used toincrease and decrease the operator demand for driving force from thepower unit 6, and a front wheel brake lever (not shown) are provided ata right end of the steering handlebars 4. The accelerator grip 9 cancomprise an accelerator operating element in some configurations of thepresent invention. Other accelerator operating elements also can beused, including but not limited to, thumb paddles and the like.

The accelerator grip 9 can be supported for generally free rotationalmovement on the steering handlebars 4, although not shown. Theaccelerator grip 9 can be provided with an accelerator operation amountdetector 11 (hereinafter simply referred to as “APS” or acceleratorposition sensor). The APS 11 detects the operation amount (e.g., therotational angle relative to a predetermined orientation relative to thehandlebars) of the accelerator grip 9.

The rear wheel 5 is supported generally rearward of the power unit 6 andthe rear wheel 5 is mechanically connected to the power unit 6 such thatthe rear wheel 5 can be driven by power from an engine 12 and byauxiliary power from a motor 13, both which are provided in theillustrated power unit 6.

In the illustrated configuration, the power unit 6 is a unit swing typeand can be supported for generally free vertical pivoting movement on abody frame by a link mechanism (not shown), which can be coupled to thefront end. As shown in FIG. 1, a cushion unit 14 can be interposedbetween the rear end of the power unit 6 and the body frame (not shown).

As shown in FIG. 2, one configuration of the power unit 6 comprises anengine 12 and a motor 13 provided at its forward end (i.e., on the rightside in FIG. 2), a belt- type continuously variable transmission 15(hereinafter simply referred to as “CVT”) extending longitudinally onthe left side of the vehicle body, an automatic centrifugal clutch 16provided at the rear end of the CVT 15, a gear-type speed reducer 18provided between the automatic centrifugal clutch 16 and an axle 17 ofthe rear wheel 5, and a control device 19 (see FIG. 3) that is used tocontrol the operation of the engine 12 and the motor 13.

A main switch 21, a start switch 22, a battery 23 and the like can beconnected to the control device 19. The start switch 22 is used to startthe engine 12. In the illustrated configuration, the start switch 22causes the motor 13 to turn such that the motor 13 can be used to startthe engine 12. Thus, when starting, the motor 13 substantially functionsas a starter motor. In other configurations, a dedicated starter motormay be used to start the engine 12.

The engine 12 preferably is a 4-cycle engine, which includes a crankcase31 shown in FIG. 2 and a cylinder (not shown) provided in front of thecrankcase 31 and extending upward. An intake system comprising athrottle valve 32 (see FIG. 3) and an exhaust system comprising amuffler 33 (see FIG. 1) can be connected to the cylinder.

The throttle valve 32 is connected to the accelerator grip 9 via a wire(not shown), and opens and closes through operation of the acceleratorgrip 9. In some configurations, a wireless system, or any other suitableconfiguration, can be used. The throttle valve 32 is provided with athrottle valve opening sensor (not shown) that is used to detect theopening or position of the throttle valve 32. The throttle valve openingsensor can be connected to an engine control section 34 of the controldevice 19 shown in FIG. 3 and transmits to the engine control section 34the opening or position of the throttle valve 32 as detected data.

The engine 12 is arranged in such that the fuel injector 35 (see FIG. 3)injects fuel into an intake passage. The fuel injection amount from thefuel injector 35 preferably is set by the engine control section 34according to the position of the throttle valve 32 and the speed of theengine 12. The speed of the engine 12 can be calculated using the numberof ignition pulses generated by an ignition system having an ignitionplug (not shown). Other configurations also can be used. The ignitiontiming of the engine 12 can be set by the engine control section 34based on the rotational angle of the crankshaft 36.

The rotational angle of the crankshaft 36 can be detected by anelectromagnetic pickup 37 (see FIG. 2), which can be attached to thecrankcase 31. The electromagnetic pickup 37 is positioned to face atooth 38 a of a rotor 38 (see FIG. 2) of the motor 13 and theelectromagnetic pickup 37 sends a signal (e.g., a detection signal) tothe engine control section 34 when the tooth 38 a is magneticallydetected.

As shown in FIG. 2, the crankshaft 36 of the engine 12 is supported onthe crankcase 31 by bearings 39, 40 for free rotation. The crankcase 31comprises a left half 41 and a right half 42. The left half 41 is formedintegrally with a longitudinally extending portion 41 a that extendsalong a left side of the rear wheel 5, to which a transmission casecover 43 can be attached.

The left half 41 of the crankcase 31 and the transmission case cover 43form, at least in part, a transmission case 44 that supports the CVT 15,the automatic centrifugal clutch 16, the gear-type speed reducer 18 andthe like. A motor housing 45 for the motor 13 also can be attached tothe right half 42 of the illustrated crankcase 31.

As shown in FIG. 2, a driving pulley 46 of the CVT 15 is mounted to anend of the crankshaft 36 on the left side of the vehicle body. Thedriving pulley 46 comprises a fixed sheave half 46 a, which is securedto the crankshaft 36, a movable sheave half 46 b, which is axiallymoveable relative to the crankshaft 36 but not capable of substantialrotation relative thereto, and a drive mechanism (not shown) that movesthe movable sheave half 46 b axially on the crankshaft 36.

The CVT 15 comprises the driving pulley 46, a driven pulley 47, which ispositioned rearwardly of the driving pulley 46, and a V-belt 48 wrappedaround both pulleys 46, 47. As is well known, the CVT 15 supplies therotation of the crankshaft 36 to the rotary shaft 49 at varying ratios.The driven pulley 47 comprises a fixed sheave half 47 a, which is fixedto the rotary shaft 49, and a movable sheave half 47 b, which is axiallymoveable, but not substantially rotationally moveable, relative to therotary shaft 49. The moveable sheave half 47 b also preferably is urgedtoward the fixed sheave half 47 a by a compression coil spring (notshown) or the like.

The rotary shaft 49 preferably is formed in the shape of a cylinder. Therotary shaft 49 preferably is supported for rotation by a bearing (notshown) on an intermediate shaft 50 that extends into a hollow portion ofthe rotary shaft 49. The intermediate shaft 50 is supported on thetransmission case 44 for rotation by bearings 51, 52. An input part 16 aof the automatic centrifugal clutch 16 preferably is connected to an endof the rotary shaft 49 on the left side of the vehicle body.

The automatic centrifugal clutch 16 comprises the input part 16 a, whichhas a clutch shoe 16 b. The automatic centrifugal clutch also comprisesa clutch outer 16 c that houses the input part 16 a. The clutch outer 16c can be secured to an end of the intermediate shaft 50 on the left sideof the vehicle body.

An end of the intermediate shaft 50 on the right side of the vehiclebody is connected to the axle 17 of the rear wheel 5 via the gear-typespeed reducer 18, which is a two-staged type. The axle 17 of the rearwheel 5 is supported for free rotation on the transmission case 44through bearings 53, 54.

With the thus constructed power unit 6, rotation of the crankshaft 36 istransmitted from the driving pulley 46 via the V-belt 48 to the drivenpulley 47 of the CVT 15, and then from the rotary shaft 49 to the inputpart 16 a of the automatic centrifugal clutch 16. As the rotation of thecrankshaft 36 increases, the rotation of the input part 16 a increases.Then, a centrifugal force increases the diameter of the clutch shoe 16b, which causes the clutch shoe 16 b to engage with the clutch outer 16c. This in turn causes the clutch outer 16 c to rotate. This rotation istransmitted from the intermediate shaft 50 via the gear-type speedreducer 18 to the axle 17 (rear wheel 5).

As shown in FIG. 2, a rotor 38 of the motor 13 to be discussed later ismounted to an end of the crankshaft 36 on the right side of the vehiclebody.

The motor 13 is intended to apply auxiliary power to the crankshaft 36,and has a function to generate electricity by being driven by the engine12. The motor 13 includes the above rotor 38 and a stator 61 fixed tothe motor housing 45, and as shown in FIG. 3, is connected to amotor/generator control section 62 of the control device 19.

The rotor 38 is made up of a boss 38 b fixed to the crankshaft 36, adisk 38 c extending radially from an end of the boss 38 b on the leftside of the vehicle body, a cylinder 38 d housing the disk 38 c, and apermanent magnet 63 secured to an end surface of the disk 38 c on theright side of the vehicle body. The tooth 38 a to be detected by theelectromagnetic pickup 37 is formed on the outer periphery of thecylinder 38 d. The motor 13 directly drives the crankshaft 36.

The stator 61 incorporates a coil 64, and is fixed to the motor housing45 in such a manner as to be partially inserted into the cylinder 38 dand face the permanent magnet 63. The stator 61 is provided on acircumference centered on the axis of the crankshaft 36.

The stator 61 of the motor 13 also incorporates an encoder 65 (see FIG.3) for detecting the speed of the rotor 38 (speed of the crankshaft 36).

The motor/generator control section 62 is intended to control when themotor 13 is supplied with electricity and the magnitude of theelectricity that is supplied. The motor/generator control section 62also switches the motor 13 being motor and generator modes of operation.As shown in FIG. 4, the motor/generator control section 62 comprises anacceleration data acquisition component 71, a rotational speed detectioncomponent 72, a rotational speed estimation component 73, a motorcontrol component 74, a charge level detection component 75, a chargingcomponent 76, a charge level determination component 77, a prechargingcomponent 78, and a timer 79.

The acceleration data acquisition component 71 preferably acquires theaccelerator operation amount (i.e., the operation angle of theaccelerator grip 9) detected by the APS 11 and the accelerator operationspeed (i.e., the speed at which the accelerator grip 9 is operated) asacceleration data.

The rotational speed detection component 72 detects the speed of theengine 12. In one configuration, the rotational speed detectioncomponent 72 is arranged to obtain the speed of the crankshaft 36 usingthe encoder 65. Instead of the speed of the crankshaft 36, therotational speed detection component 72 may detect the speed of therotor 38 of the motor 13. Also, the rotational speed detection component72 may detect the rotational speed of a rotary body directly connectedto the crankshaft 36, the rotor 38 or the like for rotation in synctherewith, or that of a rotary body (not shown) connected to thecrankshaft 36, the rotor 38 or the like via a transmission means (notshown) such as gear or chain for rotation in sync therewith. To detectthe speed of the rotor 38, the electromagnetic pickup 37 may be used.

The rotational speed estimation component 73 estimates the speed of theengine 12 at which the motor 13 is caused to generate auxiliary power.Estimation can be made such that the estimated rotational speed is therotational speed at which the automatic centrifugal clutch is completelyengaged (i.e., the engagement completion rotational speed).

For example, when the accelerator grip 9 is operated over a large angleat a rapid rate, the power from the engine 12 to be applied to theautomatic centrifugal clutch 16 becomes relatively large, which makesrelatively high the rotational speed at which the automatic centrifugalclutch 16 will be completely engaged. Thus, the engagement completionrotational speed is estimated to be relatively high. When the engagementcompletion rotational speed is not estimated and the motor 13 issupplied with electricity in conjunction with the accelerator operation,auxiliary power is generated by the motor 13 right at the start of theaccelerator operation and too large a torque is applied before theautomatic centrifugal clutch 16 has become completely engaged. Thus, theclutch shoe 16 b may slip and power may not be able to be transferred tothe drive wheel or wheels.

The rotational speed estimation component 73 estimates the engagementcompletion rotational speed based on a higher one of a provisionalrotational speed estimated based on the accelerator operation amount(hereinafter referred to as “first rotational speed”) and a provisionalrotational speed estimated based on the accelerator operation speed(hereinafter referred to as “second rotational speed”).

Now, a detailed description will be made of one manner of estimating theengagement completion rotational speed. The rotational speed estimationcomponent 73 according to this embodiment estimates the final engagementcompletion rotational speed using the maps shown in FIGS. 5(A) to 5(C).FIG. 5(A) is a map for obtaining a set value A, which is equivalent tothe first rotational speed in accordance with the accelerator operationamount. FIG. 5(B) is a map for obtaining a set value B, which isequivalent to the second rotational speed in accordance with theaccelerator operation speed. FIG. 5(C) is a map for estimating the finalengagement completion rotational speed based on the set value A and theset value B.

As shown in FIG. 5(A), the set value A preferably is set such that therotational speed becomes higher as the accelerator operation amountbecomes larger until the accelerator operation amount reaches apredetermined upper limit, and such that the rotational speed maintainsa substantially constant maximum speed once the accelerator operationamount exceeds the upper limit.

As shown in FIG. 5(B), the set value B preferably is set such that therotational speed becomes higher as the accelerator operation speedbecomes higher until the accelerator operation speed reaches apredetermined upper limit, and such that the rotational speed maintainsa substantially constant maximum speed once the accelerator operationspeed exceeds the upper limit.

The rotational speed estimation component 73 reads from the map shown inFIG. 5(A) a set value A in accordance with the accelerator operationamount acquired by the acceleration data acquisition component 71 fromthe map shown in FIG. 5(A). The rotational speed estimation component 73also reads from the map shown in FIG. 5(B) a set value B in accordancewith the accelerator operation speed acquired by the acceleration dataacquisition means 71. The rotational speed estimation component 73 thencompares the set value A and the set value B, applies the larger one ofthe set values A, B to the map shown in FIG. 5(C), and reads the finalengagement completion rotational speed as a set value from the drawing.

The motor control component 74 comprises an electricity supplyrestriction component 81 and a prerotation component 82. The motorcontrol component 74 supplies the motor 13 with a magnitude ofelectricity in accordance with the accelerator operation amount afterthe accelerator grip 9 in an idling state was operated and the speed ofthe engine 12 has reached the engagement completion rotational speed.

Whether or not the accelerator grip 9 is in an idling state is detectedusing the accelerator operation amount acquired by the acceleration dataacquisition component 71. That is, the accelerator grip 9 is determinedto be in an idling state if the accelerator operation amount is 0.

Whether or not the accelerator grip 9 has been operated is detected bydetermining whether or not the accelerator operation amount has changedfrom 0.

In supplying the motor 13 with a magnitude of electricity in accordancewith the accelerator operation amount, the motor control component 74reads a magnitude of driving current in accordance with the acceleratoroperation amount from the map such as that shown in FIG. 6 and controlsthe voltage such that the desired magnitude of driving current flowsthrough the motor 13. The motor control component 74 supplies the motor13 with electricity only when the charge level of the battery 23 isabove a minimum charge level.

The electricity supply restriction component 81 restricts the length oftime during which the motor control component 74 can supply the motor 13with electricity to a predetermined electricity supply time. Theelectricity supply time is set by an electricity supply time settingcomponent 83. That is, the electricity supply restriction component 81continues the supply of electricity to the motor 13 for the electricitysupply time and discontinues the supply of electricity to the motor 13after the electricity supply time has elapsed. The electricity supplytime preferably is counted by a timer.

The electricity supply time setting component 83 changes the electricitysupply time according to the charge level of the battery 23 detected bythe charge level detection component 75. In changing the electricitysupply time, the electricity supply time setting component 83 can use amap such as that shown in FIG. 7. FIG. 7 is a graph showing the drivingtime for a charge level of the battery 23 (battery SOC). As shown in thegraph, the electricity supply time is set to be shorter as the chargelevel of the battery 23 becomes lower. The electricity supply timesetting component 83 reads an electricity supply time in accordance withthe present charge level of the battery 23 from a map such as that shownin FIG. 7 and sends the electricity supply time to the electricitysupply restriction component 81. That is, the electricity supplyrestriction component 81 shortens the electricity supply time as thecharge level detected by the electricity supply time setting component83 becomes lower.

The prerotation component 82 is intended to reduce the likelihood of themotor 13, when not generating auxiliary power, from serving as a load onthe engine 12. The prerotation component 82 also is arranged to startenergization in order to rotate the motor 13 when the speed of theengine 12 has reached a predetermined prerotation speed. In thisembodiment, the prerotation speed is set to be lower than the speed ofthe engine 12 in an idling state (idling speed).

That is, in the hybrid motorcycle 1 according to this embodiment, theprerotation component 82 rotates the motor 13 in conjunction with therotation of the engine 12 after an engine start and when the enginespeed has reached the prerotation speed, which is lower than the idlingspeed. The speed of the engine 12 is detected by the rotational speeddetection component 72.

The charge level detection component 75 obtains a charge level (SOC) ofthe battery 23 in accordance with the open circuit voltage of thebattery 23 using a map such as the graph shown in FIG. 8, and then addsto this charge level the current amount while the battery 23 is chargingand subtracts the current amount while the battery 23 is discharging toobtain the present charge level. The battery open circuit voltage isdetected by the charge level detection component 75 while electricity inthe battery 23 is not consumed or while the battery 23 is not charged,for example when the engine is stopped. The battery 23 is charged by thecharging component 76. In one configuration, the current while chargingand the current while the battery 23 is discharging are measured by acurrent detector 84 (see FIG. 3) provided in the circuit connecting thebattery 23 and the motor/generator control section 62.

Instead of measuring and adding the charge current and the dischargecurrent each time as discussed above, a map such as that shown in FIG. 9may be used to detect the charge level of the battery 23 during engineoperation. In the map shown in FIG. 9, the charge level (SOC) of thebattery 23 is defined by the battery current and the battery voltage.The map shows the relation between the voltage between the terminals ofthe battery 23 and the current flowing through the battery 23 at eachcharge level from 0% to 100%. In the case of using this map to obtainthe charge level of the battery 23, the charge level detection component75 detects the present values of the current flowing through the battery23 and the voltage between the terminals of the battery 23, and reads acharge level (SOC) in accordance with these current and voltage valuesfrom the map.

The charging component 76 causes the motor 13 to function as a generatorsuch that it generates electricity after the electricity supply time haselapsed and charges the battery 23 with the generated electricity. Thecharging component 76 also changes the amount of electricity to begenerated according to the charge level detected by the charge leveldetection component 75. That is, the charging component 76 reduces thecharge current when the charge level of the battery 23 is relativelyhigh and increases the charge current when the charge level of thebattery 23 is relatively low.

In one configuration, the charge level determination component 77compares the charge level of the battery 23 detected by the charge leveldetection component 75 and the predetermined minimum charge level ifauxiliary power is not generated by the driving of the motor 13. Thecharge level determination component 77 also can send a control signalto the prerotation component 82 to discontinue the supply of electricityto the motor 13 and sends a control signal to the precharging component78 to start charging when the charge level of the battery 23 is lowerthan the minimum charge level. On receiving the control signal, theprerotation component 82 stops the supply of electricity to the motor13.

When the control signal is sent from the charge level determinationcomponent 77, the precharging component 78 causes the motor 13 tofunction as a generator and to generate electricity if auxiliary poweris not generated by driving of the motor 13. The charge current whilegenerating electricity is read from the map such as that shown in FIG.10 and set. The map preferably shows the charge current and thedischarge current of the battery 23 for a charge level (SOC) of thebattery 23.

As can be understood from this map, the precharging component 78according to this embodiment increases the charge current as the chargelevel of the battery 23 becomes lower when the charge level is betweenthe minimum charge level C1 and a limit value C2 lower than that. Also,the precharging component 78 performs charging at a constant maximumcharge current when the charge level is lower than the limit value C2.When the motor 13 operates as a generator while the engine 12 is inlow-speed operation, the engine control section 34 of the hybridmotorcycle 1 increases the fuel injection amount from the injector 35 tostabilize the rotation of the engine 12.

When the accelerator grip 9 is in an idling position, for example, thefuel injection amount is controlled such that the engine speed reachesthe idling speed during normal operation. When the accelerator operationamount is increased from the idling position, the engine control section34 increases the fuel injection amount according to the increase inaccelerator operation amount. Thus, since the fuel injection amount isincreased according to an increase in load due to electricity generationby the motor 13, the engine 12 is less likely to stall because of suchan increase in load due to electricity generation.

With reference now to FIGS. 11 and 12, and with additional reference toFIG. 13, operation of the motor/generator control section 62 will bedescribed.

The engine 12 is started by turning ON the main switch 21 and thenturning ON the start switch 22 in steps P1 to P3 of the flowchart shownin FIG. 11.

The timing of turning ON the main switch 21 is indicated as time T1 inFIG. 13, and the timing of turning ON the start switch 22 is indicatedas time T2 in FIG. 13.

After an engine start, the acceleration data acquisition component 71acquires acceleration data (e.g., accelerator operation amount andaccelerator operation speed) in step P4, and the charge leveldetermination component 77 determines in step P5 whether or not thecharge level of the battery 23 is lower than the minimum charge amount.

If the charge level of the battery 23 is equal to the minimum chargelevel or lower, the precharging component 78 reads a charge current forthe motor 13 from the map shown in FIG. 10 in step P6, and causes themotor 13 to function as a generator and to generate electricity so as toobtain the charge current in step P7. Then, the process returns to stepP4 to repeat the above processes. The timing of when electricitygeneration starts in step P7 is indicated as time T3 in FIG. 13.

On the other hand, if it is determined in step P5 that the charge levelof the battery 23 is higher than the minimum charge level, the processproceeds to step P8, where the driving current for the motor 13 is set.Here, the operation performed in step P8 is described with reference tothe flowchart shown in FIG. 12.

First of all, the speed of the engine 12 is detected in step S1 of theflowchart shown in FIG. 12, and energization is started to rotate themotor 13 when the engine speed has reached the prerotation speed asshown in steps S2 to S3. The prerotation speed is indicated as symbol Rin FIG. 13. Also, the timing at which the motor 13 rotates inconjunction with the rotation of the engine 12 is indicated as time T4in FIG. 13.

Subsequently, acceleration data are acquired again in step S4, and it isdetermined in step S5 whether or not an accelerator operation has beenperformed. If an accelerator operation has not been performed, theprocess returns to step S1. If an accelerator operation has beenperformed, a set value A (i.e., the first rotational speed) inaccordance with the accelerator operation amount at that time is readfrom the map shown in FIG. 5(A) in step S6 and a set value B (i.e., thesecond rotational speed) in accordance with the accelerator operationspeed at that time is read from the map shown in FIG. 5(B) in step S7.The timing at which the accelerator operation has been performed isindicated as time T5 in FIG. 13.

Then, in step S8, based on the large one of the set value A and the setvalue B (i.e., the one that brings about a higher rotational speed), thefinal engagement completion rotational speed is read as a set value fromthe map shown in FIG. 5(C). After the engagement completion rotationalspeed is estimated in this way, it is determined in step S9 whether ornot the speed of the engine 12 has reached the engagement completionrotational speed. If the speed of the engine 12 has not reached theengagement completion rotational speed, the process returns to step S4.After the speed of the engine 12 has reached the engagement completionrotational speed, the driving current for the motor 13 is read from themap shown in FIG. 6 in step S10, and the electricity supply time is readfrom the map shown in FIG. 7 in step S11. The electricity supply timebecomes shorter as the charge level of the battery 23 becomes lower.

After preparations have been made to cause the motor 13 to generateauxiliary power, the driving current is passed to the motor 13 togenerate auxiliary power by the driving of the motor 13 in step P9 ofthe flowchart shown in FIG. 11. The timing of generating auxiliary poweris indicated as time T6 in FIG. 13. At this time, the timer 79 startscounting the time. [

When the speed of the engine 12 has increased to the engagementcompletion rotational speed following the start of the acceleratoroperation (T5), the automatic centrifugal clutch 16 has becomecompletely been engaged. Thus, the resultant force of the power from theengine 12 and the auxiliary power from the motor 13 can be transmittedfrom the automatic centrifugal clutch 16 via the gear-type speed reducer18 and the axle 17 to the rear wheel 5.

As a result, the acceleration at which this vehicle starts running islarge compared to common motorcycles that run only on the power from theengine 12. Meanwhile, if the charge level of the battery 23 is lowerthan the minimum charge level, the electricity generation amount isincreased from an electricity generation amount for idling L to anelectricity generation amount for running H after the speed of theengine 12 has reached the engagement completion rotational speed, asshown in FIG. 13.

After auxiliary power is generated by the driving of the motor 13 asdiscussed above, it is determined in step P10 whether or not theelectricity supply time has elapsed from the start of the driving of themotor 13. If the electricity supply time has not elapsed, the processreturns to step P9. If the electricity supply time has elapsed, thesupply of electricity to the motor 13 is discontinued in step P11. Thetiming of stopping the supply of electricity is indicated as time T7 inFIG. 13.

After the supply of electricity to the motor 13 is discontinued, themotor 13 is functions as a generator and generates electricity in stepsP6, P7. The timing of starting the generation of electricity isindicated as time T8 in FIG. 13. The amount of electricity generated atthis time also is increased and decreased according to the charge levelof the battery 23.

Aside from when the vehicle starts running as discussed above, the motor13 is also caused to generate auxiliary power when, for example, theaccelerator grip 9 is returned to an idling position while the vehicleis running and then operated to increase the running speed from acoasting state. Thus, also at this time, the automatic centrifugalclutch 16 does not slip and high acceleration performance can beachieved with the auxiliary power by the driving of the motor 13.

In the operation example shown in FIG. 13, the operation amount of theaccelerator grip 9 is continuously increased from the start of theoperation until the vehicle starts running. If the accelerator isoperated irregularly, an operation similar to the above example whereonly the engagement completion rotational speed is different isperformed. For example, in the case where the accelerator grip 9 is oncereversed slightly at the middle of the starting operation and then thestarting operation is performed again, the operation as shown in FIG. 14is performed.

In FIG. 14, the timing of starting the reversing operation of theaccelerator grip 9 at the middle of the starting operation is indicatedas time T10, and the timing at which the accelerator grip 9 iscompletely reversed and the starting operation is started again isindicated as time T11.

As shown in FIG. 14, the estimated value, which represents theengagement completion speed, is reduced by reversing the acceleratorgrip 9, and increased by operating the accelerator grip 9 again. Also inthis case, the motor 13 generates auxiliary power when the rotationalspeed of the engine 12 has reached the engagement completion rotationalspeed (T6) from the start of the accelerator operation (T5).

In the hybrid motorcycle 1 constructed as described above, the auxiliarypower from the motor 13 is applied to the automatic centrifugal clutch16 with the automatic centrifugal clutch 16 completely engaged. Thus,the resultant force of the power from the engine 12 and the auxiliarypower from the motor 13 can be efficiently transmitted from theautomatic centrifugal clutch 16 to the rear wheel 5 side without anyloss of power in the automatic centrifugal clutch 16. Therefore,according to this embodiment, a hybrid motorcycle 1 with excellent startand acceleration performance can be manufactured.

Also, in this embodiment, an existing APS 11 that is used to control therotation of the engine 12 is used to detect the operation amount and theoperation speed of the accelerator grip 9. Thus, it is not necessary toprovide a new member for detection purposes, such as sensor or switch,in order to manufacture the hybrid motorcycle 1, which contributes tocost reduction.

In the hybrid motorcycle 1 according to this embodiment, a sensor or aswitch for detecting the completion of engagement of the automaticcentrifugal clutch 16 is not exclusively used. Thus, according to thehybrid motorcycle 1, auxiliary power can be applied with highreliability compared to requiring a dedicated sensor or switch to detectthe completion of engagement of the automatic centrifugal clutch.

In the hybrid motorcycle 1 according to this embodiment, the supply ofelectricity to the motor 13 is discontinued after the vehicle startsrunning or accelerates and when a predetermined electricity supply timehas elapsed. Thus, the consumption of electricity in the battery 23 canbe reduced compared to the case where the supply of electricity to themotor 13 is continued after the vehicle starts running or accelerates.

In the hybrid motorcycle 1 according to this embodiment, the electricitysupply time becomes shorter as the charge level of the battery 23becomes lower. Thus, the charge level of the battery 23 is not loweredexcessively. Therefore, according to the hybrid motorcycle 1, it ispossible to secure electricity for generating auxiliary power next timethe auxiliary power is needed.

In the hybrid motorcycle 1 according to this embodiment, the motor 13generates electricity after the electricity supply time has elapsed, andthe battery 23 is charged with the generated electricity In this way,according to the hybrid motorcycle 1, the battery 23 can be chargedafter electricity in the battery 23 has been consumed. Thus, it ispossible to secure sufficient electricity for supply to the motor 13next time.

The hybrid motorcycle 1 according to this embodiment is arranged to usea higher one of the first rotational speed obtained based on theaccelerator operation amount and the second rotational speed obtainedbased on the accelerator operation speed. Thus, according to the hybridmotorcycle 1, the power from the motor 13 can be applied to theautomatic centrifugal clutch 16 at an appropriate time in accordancewith the accelerator operation speed, even if the accelerator grip 9 isoperated to fully open the throttle valve 32 in order for the vehicle tostart running or accelerate. As a result, in the hybrid motorcycle 1,the power from the engine 12 and the auxiliary power from the motor 13can be more reliably transmitted to the rear wheel 5.

The hybrid motorcycle 1 according to this embodiment is arranged torotate the motor 13 in conjunction with the rotation of the engine 12after an engine start and in an operating state where the power from themotor 13 is not applied to the crankshaft 36. Thus, according to thehybrid motorcycle 1, it is possible to prevent the motor 13 from servingas a load on the engine 12 when the motor 13 is not generating auxiliarypower, which stabilizes the rotation of the engine 12 in an idlingstate.

In the hybrid motorcycle 1 according to this embodiment, the motor 13 isrotated after the start of the engine 12 and before the speed of theengine 12 reaches an idling speed, which reduces a load on the engine12. Thus, the engine 12 shifts to an idling state while rotating stablyafter an engine start, even if the motor 13 is connected to thecrankshaft 36. As a result, according to the hybrid motorcycle 1, theseries of operations, including starting the engine 12 and the vehiclestarting and acceleration, can be performed smoothly.

In the hybrid motorcycle 1 according to this embodiment, if the chargelevel of the battery 23 is low, the battery 23 can be charged whenauxiliary power from the motor 13 is not necessary, for example when thevehicle is at a halt. Thus, according to the hybrid motorcycle 1, thebattery 23 can be prevented from being over-discharged, and it ispossible to secure electricity for use to cause the motor 13 to generateauxiliary power next time.

In the above embodiment, the rotor 38 of the motor 13 is mounted on thecrankshaft 36. However, the motor 13 may be formed separately from theengine 12. In such a case, the rotary shaft of the motor 13 and thecrankshaft 36 may be connected directly or via a transmission means thatcan maintain the ratio between the speeds of both the shafts to aconstant value.

In the above embodiment, both the accelerator operation amount and theaccelerator operation speed are used to set the engagement completionrotational speed. However, only the accelerator operation amount may beused to set the engagement completion rotational speed. Also, in theabove embodiment, the driving current supplied to the motor 13 in orderto cause the motor 13 to generate auxiliary power is increased anddecreased in proportion to the accelerator operation amount. However,the driving current may be increased and decreased in consideration ofthe accelerator operation speed as well.

In the above embodiment, the present invention is applied to a scooter.However, the present invention is not limited thereto, and may beapplied to other types of vehicles, including motorcycles.

Although the present invention has been described in terms of certainembodiments, other embodiments apparent to those of ordinary skill inthe art also are within the scope of this invention. Thus, variouschanges and modifications may be made without departing from the spiritand scope of the invention. For instance, various components may berepositioned as desired. Moreover, not all of the features, aspects andadvantages are necessarily required to practice the present invention.Accordingly, the scope of the present invention is intended to bedefined only by the claims that follow.

1. A hybrid motorcycle comprising at least one wheel, a powertransmission system connected to the at least one wheel, a power unitcomprising an engine and a motor connected to a crankshaft of theengine, the motor being configured to apply auxiliary power to thecrankshaft and to generate electricity when driven by the crankshaft, anaccelerator operating element connected to the power unit, an automaticcentrifugal clutch interposed in the power transmission system betweenthe power unit and the at least one wheel, an acceleration dataacquisition component adapted to acquire as acceleration data at leastan accelerator operation amount of the accelerator operating element; arotational speed detection component that is adapted to detect arotational speed of at least one of the crankshaft and a component thatrotates synchronously with the crankshaft; a rotational speed estimationcomponent that is adapted to estimate an engagement completionrotational speed, which is a rotational speed at which the automaticcentrifugal clutch is completely engaged, based upon the accelerationdata; and a motor controller that supplies the motor with a magnitude ofelectricity in accordance with the acceleration data when the rotationalspeed detected by the rotational speed detection component has reachedthe estimated engagement completion rotational speed.
 2. The hybridmotorcycle of claim 1, wherein the acceleration data acquisitioncomponent also is adapted to acquire as acceleration data at least anaccelerator operation speed of the accelerator operating element.
 3. Thehybrid motorcycle of claim 2, wherein the rotational speed estimationcomponent estimates the engagement completion rotational speed based ona higher one of a first rotational speed and a second rotational speed,the first rotational speed being based on the accelerator operationamount and the second rotational speed being based on the acceleratoroperation speed.
 4. The hybrid motorcycle of claim 3, wherein the motorcontroller comprises a prerotation component that is adapted to rotatingthe motor in conjunction with rotation of the engine after an enginestart and in an operating state in which power from the motor is notapplied to the crankshaft.
 5. The hybrid motorcycle of claim 2, whereinthe motor controller comprises a prerotation component that is adaptedto rotating the motor in conjunction with rotation of the engine afteran engine start and in an operating state in which power from the motoris not applied to the crankshaft.
 6. The hybrid motorcycle of claim 2further comprising an electricity supply restriction component thatcontinues the supply of electricity to the motor for a predeterminedelectricity supply time and that discontinues the supply of electricityto the motor after the electricity supply time has elapsed.
 7. Thehybrid motorcycle of claim 6, wherein the motor controller comprises aprerotation component that is adapted to rotating the motor inconjunction with rotation of the engine after an engine start and in anoperating state in which power from the motor is not applied to thecrankshaft.
 8. The hybrid motorcycle of claim 6, wherein the rotationalspeed estimation component estimates the engagement completionrotational speed based on a higher one of a first rotational speed and asecond rotational speed, the first rotational speed being based on theaccelerator operation amount and the second rotational speed being basedon the accelerator operation speed.
 9. The hybrid motorcycle of claim 8,wherein the motor controller comprises a prerotation component that isadapted to rotating the motor in conjunction with rotation of the engineafter an engine start and in an operating state in which power from themotor is not applied to the crankshaft.
 10. The hybrid motorcycle ofclaim 6 further comprising a charging component that is adapted to causethe motor to generate electricity after the electricity supply time haselapsed such that a battery can be charged with the generatedelectricity.
 11. The hybrid motorcycle of claim 10, wherein the motorcontroller comprises a prerotation component that is adapted to rotatingthe motor in conjunction with rotation of the engine after an enginestart and in an operating state in which power from the motor is notapplied to the crankshaft.
 12. The hybrid motorcycle of claim 10,wherein the rotational speed estimation component estimates theengagement completion rotational speed based on a higher one of a firstrotational speed and a second rotational speed, the first rotationalspeed being based on the accelerator operation amount and the secondrotational speed being based on the accelerator operation speed.
 13. Thehybrid motorcycle of claim 12, wherein the motor controller comprises aprerotation component that is adapted to rotating the motor inconjunction with rotation of the engine after an engine start and in anoperating state in which power from the motor is not applied to thecrankshaft.
 14. The hybrid motorcycle of claim 6 further comprising acharge level detection component that is adapted to detect a chargelevel of the battery such that the electricity supply restrictioncomponent can shorten the electricity supply time as the charge leveldetected by the charge level detection component decreases.
 15. Thehybrid motorcycle of claim 14, wherein the motor controller comprises aprerotation component that is adapted to rotating the motor inconjunction with rotation of the engine after an engine start and in anoperating state in which power from the motor is not applied to thecrankshaft.
 16. The hybrid motorcycle of claim 14, wherein therotational speed estimation component estimates the engagementcompletion rotational speed based on a higher one of a first rotationalspeed and a second rotational speed, the first rotational speed beingbased on the accelerator operation amount and the second rotationalspeed being based on the accelerator operation speed.
 17. The hybridmotorcycle of claim 16, wherein the motor controller comprises aprerotation component that is adapted to rotating the motor inconjunction with rotation of the engine after an engine start and in anoperating state in which power from the motor is not applied to thecrankshaft.
 18. The hybrid motorcycle of claim 14 further comprising acharging component that is adapted to cause the motor to generateelectricity after the electricity supply time has elapsed such that thebattery can be charged with the generated electricity.
 19. The hybridmotorcycle of claim 18, wherein the motor controller comprises aprerotation component that is adapted to rotating the motor inconjunction with rotation of the engine after an engine start and in anoperating state in which power from the motor is not applied to thecrankshaft.
 20. The hybrid motorcycle of claim 18, wherein therotational speed estimation component estimates the engagementcompletion rotational speed based on a higher one of a first rotationalspeed and a second rotational speed, the first rotational speed beingbased on the accelerator operation amount and the second rotationalspeed being based on the accelerator operation speed.
 21. The hybridmotorcycle of claim 20, wherein the motor controller comprises aprerotation component that is adapted to rotating the motor inconjunction with rotation of the engine after an engine start and in anoperating state in which power from the motor is not applied to thecrankshaft.
 22. The hybrid motorcycle of claim 21, wherein a rotationstart timing at which the prerotation component rotates the motor inconjunction with rotation of the engine is set to a time after an enginestart and when an engine speed is lower than an idling speed.
 23. Thehybrid motorcycle of claim 21 further comprising a charge leveldetermination component that is adapted to determine whether or not thecharge level of the battery is lower than a predetermined minimum chargelevel; and a precharging component that is adapted to cause the motor togenerate electricity and charge the battery with the generatedelectricity after an engine start and in an operating state in whichpower from the motor is not applied to the crankshaft if the chargelevel determination component determines that the charge level of thebattery is lower than the predetermined minimum charge level.